The invention relates to a method for the operation of a vacuum generating device, having an ejector device, whose inlet is connected with an air supply conduit and whose suction side is connected with a suction channel, which is connected with a suction gripper, and which has a pressure detection device for detecting the vacuum in the suction channel, wherein the vacuum in the suction channel is regulated in that the air supply of the inlet is turned off once the vacuum has reached an upper switching value and is switched on again until the upper switching value has been reached once the vacuum drops to a lower switching value.
The invention furthermore relates to a vacuum generating device with an ejector device having an inlet, which is connected with an air supply conduit and has a suction opening, to which a suction channel is connected, which is or can be connected with a suction gripper, furthermore has a pressure detection device used for detecting the vacuum in the suction channel, and has an electronic regulating device for regulating the vacuum prevailing in the suction channel in such a way that the air supply of the inlet is switched off once the vacuum being built up has reached an upper switching value and is again switched on until the upper switching value has been reached if the vacuum has dropped to a lower switching value.
Such a vacuum generating device, as well as the method suitable for operating it, of the type mentioned ensue from DE 10 2004 031 924 B4. The vacuum generating device contains an ejector arrangement, whose inlet can be connected via an air supply conduit with a compressed air source for generating a vacuum at a suction opening which defines a suction side. The vacuum is also applied to a connected suction channel, which can be connected with a suction gripper, by means of which an object to be handled can be held and transported by means of the vacuum.
For minimizing the use of compressed air, the air supply conduit can be blocked off once a vacuum, which is a function of the situation, exists in the suction channel, and which is capable of securely gripping an object. However, because of the unavoidable leakage, the air supply is again switched on once the underpressure drops to an also preset lower switching value. Once the upper switching value has again been subsequently reached, the air supply is again switched off, and this process can be repeated several times during an operating cycle as a function of the length an object is handled, as well as of the intensity of the occurring leakage. A monitoring device exists in accordance with DE 10 2004 031 924 B4, which detects the number of the above mentioned regulating processes, so that conclusions can be drawn as to whether there is an increased leakage and therefore malfunctions exist in the system. It is furthermore possible for a monitoring device to be provided, by means of which the evacuation time for performing a self-diagnosis can be determined.
Although this type of monitoring promises to be very dependable, it makes certain demands on the processor output of the electronic evaluation device and therefore demands comparatively very costly hardware.
A control device for a suction element is disclosed in DE 10 2004 047 853 A1, which has a vacuum generation arrangement and contains an electronic module, which is in operational connection with a separate display- and/or operating device. Inter alia, the electronic module is used for monitoring parameters, such as evacuation times and air supply times, and transmits the measured parameters to the display- and/or operating device.
DE 42 29 834 C2 describes a method and a device for electrically processing vacuum pressure information, in which measured pressure values are compared with stored ones, and an error determination is made on the basis thereof.
U.S. Pat. No. 5,617,898 discloses an arrangement of fluid pressure devices, each of which has its own electronic control unit in order to relieve a connected sequencer. The fluid pressure devices can have displays for showing malfunctions.